The present invention relates to a lining for driving or return drums or pulleys for conveyor belts and any surfaces subjected to wear by friction.
It is to be understood that the word "lining" is to be taken as having its widest meaning and that the invention therefore also applies to any material which may find an application in the conveyance or storage of products which can produce wear caused by friction or contact of products in motion.
In the more precise case of driving drums for conveyor belts which are the basis of the present patent application, it will be observed that the efficiency of the drums driving the conveyor belts may be considerably increased by ensuring a high coefficient of friction between the drum and the conveyor belt, while having a favourable effect on the resistance to wear of these two components. It is for this reason that the drums in question have already been fitted with linings comprising at least partially elements of a ceramic material, and that this has been done with a view to increasing the coefficient of friction responsible for a good contact between the belt made of natural or synthetic rubber and the drum.
This is extremely important when the conveyor belts work outdoors where dampness, water, mud, ice and certain other factors have an unfavourable effect on the proper functioning of the installation.
Water and dampness in general have a very unfavourable effect on the efficiency of a conveying plant consisting of a conveyor belt, a driving drum and several auxiliary drums, and this is clearly because of a poor coefficient of friction between the drums and the belts.
All linings of this type must satisfy the requirements in the following list:
(a) increase in the adhesion between the drum and the conveyor belt, PA1 (b) only slight wear of the lining, PA1 (c) only slight wear of the conveyor belt, PA1 (d) protection against abrasion and impacts from the metallic surfaces on to which these linings are applied.
Known linings, generally used until now, are made from natural or synthetic rubbers, from polyurethane or from equivalent synthetic materials providing a fairly pronounced elasticity. They may have channels or grooves and may or may not be covered with ceramic pads generally having rough surfaces. The purpose of the channels or grooves is to evacuate water as quickly as possible and to prevent aquaplaning when working in conditions which are very damp or involve a lot of water.
Similarly, very pronounced sliding occurs when the conveyor belt is working under normal conditions but at a steep angle.
The presence of rough ceramic pads on the surface of a rubber lining considerably increases the coefficient of friction but only as long as the roughness or geometrical shapes have not been smoothed out by wear or as long as the roughness has not been clogged up by mud, dust, etc. In any case, the linings will have channels or grooves allowing water to be evacuated.
The aim of the invention is therefore to produce linings for drums or pulleys which overcome the disadvantages, the main examples of which have been described above.
In order to achieve this aim in conformity with the invention, the lining according to the invention consists of an elastic material incorporated in which are porous ceramic elements projecting out of the surface of the lining.
Still according to the invention, the aforesaid porous ceramic elements are distributed in such a way as to create between them channels for the evacuation of water.
A noteworthy characteristic of the invention lies in the fact that the porous ceramic elements consist of particles which are bound to each other while allowing sufficient space to remain between the particles to let the water penetrate and then be evacuated under the effect of the centrifugal force.
In a first embodiment, the aforesaid porous ceramic elements are anchored to the surface of the elastic material forming the lining.
In another embodiment, the aforesaid porous ceramic elements are anchored at various depths within the elastic material forming the lining.
The term "elastic material" here denotes a natural or synthetic, polymerised or vulcanised, elastomer.